Manufacturing process for a prepreg with a carrier, prepreg with a carrier, manufacturing process for a thin double-sided plate, thin double-sided plate and manufacturing process for a multilayer-printed circuit board

The present invention relates to a manufacturing process for a prepreg with a carrier, a prepreg with a carrier, and a manufacturing process for a multilayer-printed circuit board. This invention also relates to a process for manufacturing a thin double-sided plate, a thin double-sided plate, and a process for manufacturing a multilayer-printed circuit board having a thin double-sided plate.

Recently, there have been needed high-density, densely mounted, and thinner multilayer-printed circuit boards.

A multilayer-printed circuit board is typically manufactured by a build-up method. In the build-up method, to provide an inner-layer circuit board, a circuit is formed on a metal-foiled laminated plate which is prepared by laminating a prepreg and a metal foil and then pressing the laminate under heating. Then, on both sides of the inner-layer circuit board, an insulating layer, which is so-called build-up materials, and a conductor circuit layer are alternately laminated.

When a multilayer-printed circuit board is of a large size or is mounted with semiconductor components such as a flip chip with a fine pitch, it requires adequate mechanical strength to ensure mounting reliability. It may be achieved by using a thicker inner-layer circuit board, which may, however, lead to a problem of increase in a total thickness of the multilayer-printed circuit board because of increase in the number of layers associated with higher integration and more densified mounting.

Thus, there has been proposed a technique that a prepreg is used as a build-up material for providing mechanical strength by means of the base material of the prepreg to ensure mounting reliability while achieving a thinner inner-layer circuit board (for example, see Japanese Laid-open Patent Publication No. 2004-342871).

A prepreg can be built up on an inner-layer circuit board by laminating the inner-layer circuit board and the prepreg and then pressing the laminate under heating by a flat press for curing, or by compressing an inner-layer circuit board and a prepreg by a roll laminator and then curing the product by a heating/drying apparatus.

In the method using a flat press, a resin during pressing under heating is relatively more flowable, so that the insulating layer in the prepreg tends to change its shape.

On the other hand, the method using a roll laminator can control thickness precision for an insulating layer formed. Thus, a desired insulating layer is easily formed by using the method and the method is advantageously efficient in productivity because it can be continuously conducted. It may be, therefore, effective to use a prepreg excellent in thickness precision and impregnating properties in the method using a roll laminator.

However, in a conventional process for manufacturing a prepreg, for example, a process where a textile fabric base material is immersed in a resin varnish for impregnation and then dried using a typical coater, it is difficult to ensure thickness precision due to tendency to generation of striped irregularity in a coating direction.

To solve the problem, there has been disclosed a process for manufacturing a prepreg with excellent thickness precision wherein an insulating resin with a carrier is laminated on both sides of a textile fabric base material (for example, see Japanese Laid-open Patent Publication No. 2004-123870).

Patent Document 1: Japanese Laid-open Patent Publication No. 2004-342871

Patent Document 2: Japanese Laid-open Patent Publication No. 2004-123870

A prepreg with excellent thickness precision may be prepared by a process where an insulating resin with a carrier is laminated on both sides of a textile fabric base material.

In the process, the textile fabric base material is, however, insufficiently impregnated with a resin component, often giving a prepreg with residual voids. Thus, when such a prepreg is used in manufacturing a multilayer-printed circuit board, insulation reliability may be deteriorated.

Furthermore, a multilayer-printed circuit board is used, for example, in a substrate for a package on which semiconductor components are mounted. Development in densifying and thinning technique has increased the number of applications of new packages such as BGA, and a substrate for a package has been required to be heat resistant and less thermally expansible. Thus, there has been needed a prepreg capable of endowing the package with such properties.

In view of the background described above, the present invention provides a process for manufacturing a prepreg with a carrier exhibiting excellent impregnating properties and thickness precision, which is particularly suitably used for preparing a build-up type multilayer-printed circuit board, and provides a prepreg with a carrier prepared by the manufacturing process, and a process for manufacturing a multilayer-printed circuit board utilizing the prepreg with a carrier.

The invention also provides a manufacturing process for a thin double-sided plate and a thin double-sided plate prepared by the process. The above objectives can be achieved by the following aspects (1) to (40) of the present invention.

(1) A process for continuously manufacturing a prepreg with carriers comprising an insulating resin layer having a backbone material of a textile fabric,

(a) laminating each insulating resin layer side of a first and a second carriers comprising an insulating resin layer on one side on the both sides of the textile fabric, respectively, to form a laminate and bonding them under a reduced pressure, and

(b) after the bonding, heating the laminate at a temperature equal to or higher than a melting point of the insulating resin.